Hard floor cleaning these days is done by first vacuuming the floor, followed by mopping it. Vacuuming removes the coarse dirt, while mopping removes the stains. From the state of the art many appliances, especially targeting the professional cleaning sector, are known that claim to vacuum and mop in one go. Appliances for the professional cleaning sector are usually specialized for big areas and perfectly flat floors. They rely on hard brushes and suction power to get water and dirt from the floor. Appliances for home use often use a combination of a hard brush and a double-squeegee nozzle. Like the appliances for the professional sector these products use the brush to remove stains and the squeegees in combination with an under-pressure to lift the dirt from the floor.
The squeegee elements are usually realized by a flexible rubber lip that is attached to the bottom of the cleaning device and merely glides over the surface to be cleaned, thereby pushing or wiping dirt particles and liquid across or off the surface to be cleaned. An under-pressure, usually generated by a vacuum aggregate, is used to ingest the collected dirt particles and liquid.
Many of the known prior art vacuum cleaners use an agitator (also denoted as adjutator) with stiff brush hairs to agitate the floor. These stiff hairs show a rather good scrubbing effect, which enable to use the brush particularly for removing stains. However, the performance on drying the floor is rather low, since such an agitator is not able to lift liquid from the floor. The object of vacuuming and mopping the floor with actively sprayed water all in one go is therefore not solved with these devices in a sufficiently satisfactory manner.
WO 2010/041184 A1, which has been filed in the name of the applicant, shows an alternative cleaning device which is able to pick up dirt and liquid from the floor in one go. The cleaning device disclosed therein makes use of two separate brushes that are aligned in parallel to each other. These brushes rotate at high speeds, one running clockwise and the other one counterclockwise. In this way, the adjacent peripheries travelling together with a sufficiently high velocity to project the dirt and/or liquid particles vertically upwards with a considerable force in the form of a substantially flat jet. In contrast to the prior art devices named before, the two brushes used therein are not realized as agitators, but are equipped with flexible soft bristles.
It has been identified that such two rotating brushes generate an unwanted turbulent air blow outside the nozzle housing, which occurs as a result of the fact that the soft brushes are deflected/indented by the surface to be cleaned. The brushes thereby act as a kind of gear pump which pumps air from the inside of the nozzle housing to the outside. This blowing effect can cause dirt and/or liquid particles to be blown away from the brushes, such that they are out of reach from the brushes and could then not be ingested by the vacuum cleaner.
WO 2010/041184 A1 has found a solution to account for this unwanted blowing effect. Therein, two deflectors are used, one for each brush. These deflectors deflect/indent the bristles of the brush at a position, seen in rotation direction, before the bristles of the brush contact the surface to be cleaned. These deflectors have the function to press the bristles of the brush together by deflecting them. In this way air, which is present in the space between the bristles, is pushed out of the space. When the bristles are, after leaving the deflectors, moved apart from each other again, the space in between the bristles increases so that air will be sucked into brush, wherein an under-pressure is created that sucks in the dirt and/or liquid particles. This under-pressure compensates for the air flow that is generated by the rotating brushes.
U.S. Pat. No. 1,209,384 A discloses a street sweeping machine comprising a single rotary brush and an up-curved sheet metal hood that is mounted over the upper forward portion of the brush in order to facilitate gathering of the dirt by the brush and to control the discharge therefrom.
U.S. Pat. No. 4,310,944 A discloses a powered sweeping machine, particularly suitable for efficiently removing light and heavy weight litter from surfaces such as parking lots, warehouse floors and the like. The machine includes a main frame carrying a hopper and a powered brush. The brush operates through an opening in the lower side of a brush housing. The hopper is separated into a debris receiving compartment and a filter compartment. An air fan and an associated duct recirculates air from the far end of the debris compartment to a zone adjacent the brush.
AU 29608 89 A discloses a further industrial sweeping apparatus.